Methods of making intermediates from polyhydroxyalkanoates

ABSTRACT

Methods of forming intermediates from PHAs are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e)(1) to U.S.Provisional Patent Application Ser. No. 60/341,546, filed Dec. 18, 2001,and entitled “Process of Making Chemical Intermediates from NaturallyOccurring Polyhydroxyalkanoates,” and to U.S. Provisional PatentApplication Ser. No. 60/402,469, filed Aug. 9, 2002, and entitled“Alkanoic and Alkenoic Acid Esters and Methods of Making Same,” both ofwhich are incorporated by reference.

TECHNICAL FIELD

The invention generally relates to methods of making intermediates frompolyhydroxyalkanoates (PHAs).

BACKGROUND

Various chemical intermediates, such as esters, amides, diols and acids,are known to be useful. For example, certain chemical intermediates canbe used as solvents (e.g., coalescing solvents, cleaning solvents),process additives, plasticizers, surface active agents, in theformulation of products (e.g., industrial products, consumer products),and/or monomers in a polymerization process.

SUMMARY

The invention generally relates to methods of making intermediates fromPHAs.

In one aspect, the invention features a method. The method includestreating a biomass containing a PHA to form a PHA intermediate, andremoving at least about 10 weight percent of the PHA intermediate fromthe biomass.

In another aspect, the invention features a method that includescontacting a PHA with an aprotic catalyst to form an ester. The esterhas only one monomer unit from the PHA.

In a further aspect, the invention features a method that includestreating a PHA-containing non-lyophilized biomass to form an ester, andremoving at least some of the ester from the biomass.

In one aspect, the invention features a method that includes combining aPHA with an alcohol to form an ester. The PHA and the alcohol form acombination containing less than about one milliliter of solvent otherthan the alcohol per gram of PHA.

In another aspect, the invention features a method that includescombining a PHA and an alcohol to form an ester from a PHA. The percentyield of the ester is at least about 50%, and a ratio of the moles ofthe alcohol per mole of PHA monomer unit is less than about 20.

In a further aspect, the invention features a method that includesheating a PHA to a temperature of at least about 180° C. to form anester.

In one aspect, the invention features a method that includes treating aPHA to form an amide. The amide has only one repeat unit from the PHA.

In another aspect, the invention features a method that includestreating a biomass containing a PHA to form an amide.

In a further aspect, the invention features a method that includesheating a PHA to a temperature of at most about 90° C. to form an amide.The percent yield of the amide is at least about 50%.

In one aspect, the invention features a method that includes heating aPHA to form a cyclic amide.

In another aspect, the invention features a method that includeshydrogenolyzing a PHA to form a diol.

In one aspect, the invention features a method that includes heating abiomass containing a PHA to form an alkenoic acid. The percent yield ofalkenoic acid from the PHA is at least about 50%.

In another aspect, the invention features a method that includes heatinga PHA to a temperature of at least about 200° C. to form an alkenoicacid.

In a further aspect, the invention features a method that includestreating a PHA to form acrylic acid. The PHA has at least one3-hydroxypropionate monomer.

In one aspect, the invention features a method. The method includesheating a mixture containing a first portion of a PHA to form a firstportion of an alkenoic acid, and adding, after forming the first portionof the alkenoic acid, a second portion of the PHA to the mixture.

The methods can further include using the intermediate(s) (e.g., as asolvent, as a process additive, as a monomer to form a polymer, and/orin the formulation of a product).

In certain embodiments, the methods can be relatively nontoxic,relatively environmentally friendly, relatively sustainable, relativelysimple and/or relatively inexpensive.

In some embodiments, the intermediates can be formed at relatively highyield.

In certain embodiments, the methods can result in the formation of achiral intermediate. This can be advantageous, for example, if theusefulness (e.g., commercial usefulness) of the intermediate depends onthe chirality of the intermediate.

In some embodiments, the PHAs can serve as non-fossil carbon basedfeedstocks for materials (PHA intermediates).

Features, aspects and advantages of the invention are in the descriptionand claims.

DETAILED DESCRIPTION

In general, the methods include treating a PHA to form a PHAintermediate. The methods optionally include using the PHA intermediate(e.g., as a solvent, as a process additive, as a monomer to form apolymer, a precursor to form another product, and/or in the formulationof a product).

A PHA contains multiple monomer units. Typically, a PHA contains atleast about 500 monomer units (e.g., at least about 1,000 monomerunits). In some embodiments, when a PHA is a homopolymer, the multiplemonomer units contained in the PHA are all the same. In certainembodiments, when the PHA is a copolymer, the multiple monomer unitscontained in the PHA include at least two different monomer units.

A PHA intermediate is a compound that has fewer monomer units thanpresent in the PHA from which the PHA intermediate was formed. In someembodiments, a PHA intermediate contains only one monomer unit from thePHA. In certain embodiments, a PHA intermediate can contain multiplemonomer units (e.g., from two monomer units to 500 monomer units, fromtwo monomer units to 400 monomer units, from two monomer units to 300monomer units, from two monomer units to 200 monomer units, from twomonomer units to 100 monomer units, from two monomer units to 50 monomerunits, from two monomer units to 40 monomer units, from two monomerunits to 25 monomer units), but the PHA intermediate contains fewermonomer units than present in the PHA itself. Examples of PHAintermediates include esters, amides, diols and acids.

As explained below, treating a PHA to form a PHA intermediate generallyincludes heating the PHA under appropriate conditions (e.g., in thepresence of a reactant, in the presence of a solvent, in the presence ofa catalyst, and/or at elevated pressure).

In some embodiments, the methods result in a relatively high yield ofthe PHA intermediate. For example, the percent yield of PHA intermediatefrom the PHA can be at least about 30% (e.g., at least about 35%, atleast about 40%, at least about 45%, at least about 50%, at least about55%, at least about 60%, at least about 65%, at least about 70%, atleast about 75%, at least about 80%, at least about 85%, at least about90%, at least about 95%, at least about 98%). The percent yield of a PHAintermediate from a PHA is determined as follows. The number of moles ofthe PHA intermediate is multiplied by the number of monomer units permole of the PHA intermediate, which provides a value A. The number ofmoles of PHA is multiplied by the number of monomer units per mole ofPHA, which provides a value B. The value A is divided by the value B toprovide a value C, which is multiplied by 100%.

In embodiments in which a chiral PHA is treated to form a chiral PHAintermediate, the percent chirality yield of the chiral PHA intermediatecan be relatively high. For example, the percent chirality yield of achiral PHA intermediate from a chiral PHA can be at least about fivepercent (e.g., at least about 10%, at least about 25%, at least about50%, at least about 75%, at least about 85%, at least about 90%, atleast about 95%, at least about 98%). The percent chirality yield of achiral PHA intermediate from a chiral PHA is determined as follows. Thenumber of moles of the chiral PHA intermediate is multiplied by thenumber of chiral monomer units per mole of the chiral PHA intermediate,which provides a value D. The number of moles of chiral PHA ismultiplied by the number of chiral monomer units per mole of the chiralPHA, which provides a value E. The value D is divided by the value E toprovide a value F, which is multiplied by 100%.

As used herein, the term chiral PHA refers to a PHA in which at leastsome of the monomer units are chiral, and all the chiral monomer unitsin the PHA have the same chirality (e.g., R configuration or Sconfiguration). As used herein, the term chiral PHA intermediate refersto a PHA intermediate that is formed from a chiral PHA and that has thesame chirality as the chiral monomer units in the chiral PHA.

In certain embodiments in which the PHA is derived from biomass and atleast some of the PHA is not removed from the biomass before beingtreated to form the PHA intermediate, the methods can include removingat least a portion of the PHA intermediate from the biomass. Forexample, at least about 10 weight percent (e.g., at least about 20weight percent, at least about 30 weight percent, at least about 40weight percent, at least about 50 weight percent, at least about 60weight percent, at least about 70 weight percent, at least about 80weight percent, at least about 90 weight percent, at least about 95weight percent, at least about 98 weight percent) of the PHAintermediate can be removed from the biomass.

PHAs

In certain embodiments, a PHA has at least one monomer unit with thestructure:

n is zero or an integer (e.g., one, two , three, four, five, six, seven,eight, nine, 10, 11, 12, 13, 14, 15, etc.). Each of R₁, R₂, R₃, R₄, R₅and R₆ is independently a hydrogen atom, a halogen atom or a hydrocarbonradical. A hydrocarbon radical contains at least one carbon atom (e.g.,one carbon atom, two carbon atoms, three carbon atoms, four carbonatoms, five carbon atoms, six carbon atoms, seven carbon atoms, eightcarbon atoms, etc.). A hydrocarbon radical can be saturated orunsaturated, substituted or unsubstituted, branched or straight chained,and/or cyclic or acyclic. Examples of substituted hydrocarbon radicalsinclude halo-substituted hydrocarbon radicals, hydroxy-substitutedhydrocarbon radicals, nitrogen-substituted hydrocarbon radicals andoxygen-substituted hydrocarbon radicals. Examples of hydrocarbonradicals include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl anddecyl.

Examples of monomer units include 3-hydroxybutyrate,3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxyhexanoate,3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxynonaote,3-hydroxydecanoate, 3-hydroxydodecanoate, 3-hydroxytetradecanoate,3-hydroxyhexadecanoate, 3-hydroxyoctadecanoate, 4-hydroxybutyrate,4-hydroxyvalerate, 5-hydroxyvalerate, and 6-hydroxyhexanoate.

In some embodiments, a PHA can be a homopolymer (all monomer units arethe same). Examples of PHA homopolymers include poly 3-hydroxyalkanoates(e.g., poly 3-hydroxypropionate, poly 3-hydroxybutyrate, poly3-hydroxyhexanoate, poly 3-hydroxyheptanoate, poly 3-hydroxyoctanoate,poly 3-hydroxydecanoate, poly 3-hydroxydodecanoate), poly4-hydroxyalkanoates (e.g., poly 4-hydroxybutyrate), poly5-hydroxyalkanoates (e.g., poly 5-hydroxypentanoate), poly6-hydroxyalkanoates (e.g., poly 6-hydroxyhexanoate) and polylactic acid.Another example of a homopolymer of interest is polyglycolic acid (forwhich there is only one carbon other than the carbonyl carbon in themonomer structure).

In certain embodiments, a PHA can be a copolymer (contain two or moredifferent monomer units). Examples of PHA copolymers include poly3-hydroxybutyrate-co-3-hydroxyprlopionate, poly3-hydroxybultyrate-co-3-hydroxyvalerate, poly3-hydroxybutyrate-co-3-hydroxyhexanoate, poly3-hydroxybutyrate-co-4-hydroxybutyrate, poly3-hydroxybutyrate-co-4-hydroxyvalerate, poly3-hydroxybutyrate-co-6-hydroxyhexanoate, poly3-hydroxbutyrare-co-3-hydroxyheptanoate, poly3-hydroxybutyrate-co-3-hydroxyoctanoate, poly3-hydroxybutyrate-co-3-hydrocydecanoate, ploy3-hydroxybutyrate-co-3-hydroxydecanoate, poly3-hydroxybutyrate-co-3-hydroxyoctanoate-co-3-hydroxydecanoate, poly3-hydroxydecanoate-co-3-hydroxyoctanoate, and poly3-hydroxybutyrate-co-3-hydroxyoctadecanoate. Although examples of PHAcopolymers having two different monomer units have been provided, a PHAcan have more than two different monomer units (e.g., three differentmonomer units, four different monomer units, five different monomerunits, six different monomer units, seven different monomer units, eightdifferent monomer units, nine different monomer units, etc.).

In certain embodiments, the PHA is derived from biomass, such as plantbiomass and/or microbial biomass (e.g., bacterial biomass, yeastbiomass, fungal biomass). Biomass-derived PHA can be formed, forexample, via enzymatic polymerization of the monomer units. Typically,the biomass is non-lyophilized. The biomass can be formed of one or moreof a variety of entities. Such entities include, for example, microbialstrains for producing PHAs (e.g., Alcaligenes eutrophus (renamed asRalstonia eutropha), Alcaligenes latus, Azotobacter, Aeromonas,Comamonas, Pseudomonads), genetically engineered organisms, preferablycontaining no recombinant plasmids, for producing PHAs (e.g.,Pseudomonas, Ralstonia, Escherichia coli, Klebsiella), yeasts forproducing PHAs, and plant systems for producing PHAs. Such entities aredisclosed, for example, in Lee, Biotechnology & Bioengineering 49:1-14(1996); Braunegg et al., (1998), J. Biotechnology 65: 127-161; Madison,L. L. and Huisman, G. W. (1999), Metabolic Engineering ofPoly(3-Hydroxyalkanoates): From DNA to Plastic. Microbiol. Mol. Biol.Rev. 63, 21-53; and Snell and Peoples 2002, Metabolic Engineering 4:29-40, which are hereby incorporated by reference.

In some embodiments in which the PHA is derived from biomass, most ofthe PHA that is treated to form the PHA intermediate is not removed fromthe biomass before being treated to form the intermediate. For example,in certain embodiments, less than about 50 weight percent (e.g., lessthan about 40 weight percent, less than about 30 weight percent, lessthan about 20 weight percent, less than about 10 weight percent, lessthan about weight percent five weight percent, less than about threeweight percent, less than about one weight percent, about zero weightpercent) of the PHA that is treated to form the PHA intermediate isremoved from the biomass before being treated to form the PHAintermediate.

In certain embodiments in which the PHA is derived from biomass, most ofthe PHA that is treated to form the PHA intermediate is removed from thebiomass before being treated to form the PHA intermediate. For example,in some embodiments, at least about 60 weight percent (at least about 70weight percent, at least about 80 weight percent, at least about 90weight percent, at least about 95 weight percent, at least about 98weight percent, about 100 weight percent ) of the PHA that is treated toform the PHA intermediate is removed from the biomass before beingtreated to form the PHA intermediate.

Esters

Treating a PHA to form an ester (e.g., an alkanoic acid ester, analkenoic acid ester) generally includes combining the PHA with analcohol (e.g., a monohydric alcohol, a polyhydric alcohol) andoptionally a catalyst (e.g., a protic catalyst, an aprotic catalyst),and exposing the PHA to elevated temperature and/or elevated pressure.

The alcohol can be represented by the structure R₇OH, where R₇ is ahydrocarbon radical that contains one or more carbon atoms (e.g., onecarbon atom, two carbon atoms, three carbon atoms, four carbon atoms,five carbon atoms, six carbon atoms, seven carbon atoms, eight carbonatoms, etc.). R₇ can be saturated or unsaturated, substituted orunsubstituted, branched or straight chained, and/or cyclic or acyclic.Examples of substituted hydrocarbon radicals include halo-substitutedhydrocarbon radicals, hydroxy-substituted hydrocarbon radicals,nitrogen-substituted hydrocarbon radicals and oxygen-substitutedhydrocarbon radicals. Examples of hydrocarbon radicals include methyl,ethyl, propyl, butyl, 2-ethylhexyl, isopropyl, isobutyl, tertiary butyl,hexyl, octyl, cyclohexyl, decyl, dodecyl, stearyl, oleyl, linolyl andlinolenyl.

Examples of alcohols include methanol, ethanol, propanol, butanol,2-ethylhexanol, cyclohexanol, decyl alcohol, dodecyl alcohol, isopropylalcohol, isobutyl alcohol, dodecyl alcohol, stearyl alcohol, oleylalcohol, linolyl alcohol, linolenyl alcohol, propylene glycol, glycerol,ethylene glycol, propylene glycol, 1,2-propane diol, 1,3-propane diol,1,3-butane diol, 1,4-butane diol, 1,6-hexane diol, glycerol, erythritol,pentaerythritol, dipentaerythritol, thrimethylol propane, xylose,sucrose, dextrose and triethanolamine.

In certain embodiments, an ester formed by treating the PHA is analkanoic acid ester. In some embodiments, an alkenoic acid ester can berepresented by the structure:

y is less than the number of monomer repeat units in the PHA. In someembodiments, y is from one to 499 (e.g., from one to 399, from one to299, from one to 199, from one to 99, from one to 49, from one to 39,from one to 24). In certain embodiments, y is zero.

Examples of alkanoic acid esters include methyl 3-hydroxybutyrate, ethyl3-hydroxybutyrate, methyl 3-hydroxypropionate, ethyl 3-hydroxypropionate, methyl 4-hydroxybutyrate, ethyl 4-hydroxybutyrate,cyclohexyl 3-hydroxybutyrate, cyclohexyl 4-hydroxybutyrate, stearyl4-hydroxybutyrate and stearyl 3-hydroxybutyrate.

In some embodiments, an ester formed by treating a PHA is an alkenoicacid ester. In certain embodiments, an alkenoic acid ester can berepresented by the structure:

Without wishing to be bound by theory, it is believed that alkenoic acidesters can be formed, for example, in a dehydration reaction that canoccur prior or subsequent to alcoholysis of the PHA or PHA intermediateester bond, resulting in formation of one or more carbon-carbon doublebonds. In certain embodiments (e.g., when n is zero), alkenoic acidesters are formed when one or more of R₁, R₂, R₃ and R₄ (e.g., one orboth of R₃ and R₄) is a hydrogen atom.

Examples of alkenoic acid esters include ethyl crotonate, methylcrotonate, butyl crotonate, 2-ethyl hexyl crotonate, ethyl 2-octenoateand ethyl 2 pentenoate.

As noted above, the ester is generally formed by combining the PHA withan alcohol, and exposing the PHA to elevated temperature and/or elevatedpressure.

In general, the amount of alcohol used can be selected as desired. Incertain embodiments (e.g., when it is desirable to form an ester forwhich y=0), at least about one mole (e.g., at least about two moles, atleast about four moles) of alcohol is used per mole of monomer unit inthe PHA and/or at most about 20 moles (e.g., at most about 10 moles, atmost about six moles) of alcohol are used per mole of PHA monomer unit.For example, from about two moles to about 20 moles (e.g., from abouttwo moles to about 10 moles) of alcohol can be used per mole of PHAmonomer unit. In some embodiments (e.g., when it is desirable to formester for which y>0), less than one mole (e.g., less than about 0.9mole, less than about 0.75 mole, less than about 0.5 moles) of alcoholis used per mole of monomer unit in the PHA.

The temperature can generally be selected as desired. Typically, thetemperature greater than about 25° C. In some embodiments, thetemperature can be at least about 160° C. (e.g., at least about 170° C.,at least about 180° C.). In certain embodiments, the temperature can beat most about 220° C. (e.g., at most about 210° C., at most about 200°C.). For example, the temperature can be from about 160° C. to about220° C. (e.g., from about 170° C. to about 210° C., from about 170° C.to about 200° C.).

Generally, the pressure can be selected as desired. Typically, thepressure is greater than about 14 psig. In certain embodiments, thepressure can be at least about 50 psig (e.g., at least about 100 psig).In some embodiments, the pressure can be at most about 500 psig (e.g.,at most about 250 psig). For example, the pressure can be from about 50psig to about 500 psig. Typically, elevated pressure is achieved usingan inert gas (e.g., nitrogen, helium, argon, krypton, xenon, etc.).

In certain embodiments, the PHA can be treated while using relativelylittle solvent (e.g., relatively little halogenated solvent) other thanthe alcohol. For example, the total amount of solvent other than thealcohol present during the treatment of the PHA to form the ester can beless than one milliliter (e.g., less than about 0.9 milliliter, lessthan about 0.8 milliliter, less than about 0.7 milliliter, less thanabout 0.6 milliliter, less than about 0.5 milliliter, less than about0.4 milliliter, less than about 0.3 milliliter, less than about 0.2milliliter, less than about 0.1 milliliter, less than about 0.05milliliter, about zero milliliter) per gram of PHA.

In certain embodiments, the amount of undesired byproducts is relativelysmall. For example, in some embodiments it is desired to form analkanoic acid ester, alkenoic byproducts can be undesired. In someembodiments, the percent yield of undesirable byproducts (e.g., alkenoicbyproducts) from the PHA is less than about 10% (e.g., less than abouteight percent, less than about five percent, less than about threepercent, less than about one percent).

In some embodiments, the PHA treatment to form the ester is performed inthe absence of a catalyst.

In certain embodiments, the PHA treatment to form the ester is performedin the presence of an appropriate catalyst. In general, the catalyst canbe a protic catalyst or an aprotic catalyst. Examples of proticcatalysts include sulfuric acid, para-toluene sulfonic acid,hydrochloric acid and phosphoric acid. Examples of aprotic catalystsinclude certain transesterification catalysts (e.g., metal-containingtransesterification catalysts), such as, tin compounds (e.g., dibutyltindilaurate, stannous oxide, dibutyl tin oxide, dibutyl tin chloride),titanium compounds (e.g., tetraalkoxy titanates, ethanolamine complexedwith titanium), zinc compounds (e.g., zinc acetate, zinc chloride) andclays (e.g. montmorillonite K10 clay). In some embodiments, more thanone catalyst is used.

Generally, in embodiments in which a catalyst is used, the amount ofcatalyst can be selected as desired. In some embodiments, the catalystcan be at least about 0.1 weight percent (e.g., at least about 0.25weight percent, at least about 0.5 weight percent, at least about oneweight percent) of the total amount of PHA present when the catalyst isadded. In certain embodiments, the catalyst can be at most about 10weight percent (e.g., at most about five weight percent, at most aboutthree weight percent) of the total amount of PHA present when thecatalyst is added. For example, the catalyst can be from about 0.1weight percent to about 10 weight percent (e.g., from about 0.25 weightpercent to about five weight percent of the total amount of PHA presentwhen the catalyst is added.

In some embodiments, while using a relatively small amount of alcoholrelative to PHA, an ester can be formed from the PHA at a relativelyhigh percent yield. As an example, while using less than about 20 molesof alcohol per mole of PHA monomer repeat unit, the percent yield ofester from the PHA is at least about 50% (e.g., at least about 60%, atleast about 70%, at least about 80%, at least about 90%, at least about95%, at least about 98%). As another example, while using less thanabout 10 moles of alcohol per mole of PHA monomer repeat unit, thepercent yield of ester is at least about 50% (e.g., at least about 60%,at least about 70%, at least about 80%, at least about 90%, at leastabout 95%, at least about 98%). As a further example, while using lessthan about five moles of alcohol per mole of PHA monomer repeat unit,the percent yield of ester from the PHA is at least about 50% (e.g., atleast about 60%, at least about 70%, at least about 80%, at least about90%, at least about 95%, at least about 98%). As an additional example,while using from about one mole of alcohol per mole of PHA monomerrepeat unit to about five moles of alcohol per PHA monomer repeat unit,the percent yield of ester from the PHA is at least about 50% (e.g., atleast about 60%, at least about 70%, at least about 80%, at least about90%, at least about 95%, at least about 98%).

The methods can further include isolating at least a portion of theester formed by treating the PHA. For example, in embodiments in whichthe PHA is derived from biomass and the PHA is not removed from thebiomass before being treated to form the ester, the methods can includeremoving at least a portion (e.g., at least about 10 weight percent, atleast about 20 weight percent, at least about 30 weight percent, atleast about 40 weight percent, at least about 50 weight percent, atleast about 60 weight percent, at least about 70 weight percent, atleast about 80 weight percent, at least about 90 weight percent, atleast about 95 weight percent, at least about 98 weight percent) of theester from the biomass.

In embodiments in which the PHA is a PHA copolymer, multiple esters canbe formed, corresponding to the different monomer units in the PHAcopolymer and the hydrocarbon unit in the alcohol. For example, the PHAcan be poly 3-hydroxybutyrate-co-3-hydroxypropionate, the alcohol can bemethanol, and the esters can be methyl 3-hydroxybutyrate and methyl3-hydroxypropionate.

In embodiments in which a PHA homopolymer is combined with differentalcohols and treated as described above, multiple esters can be formed,corresponding to the monomer unit contained in the PHA homopolymer andthe hydrocarbon units from the alcohols. For example, the PHA can bepoly 3-hydroxybutyrate, the alcohols can be methanol and ethanol, andthe esters can be methyl 3-hydroxybutyrate and ethyl 3-hydroxybutyrate.

In embodiments in which PHA copolymer is combined with differentalcohols, multiple esters can be formed, corresponding to the differentmonomer units in the PHA copolymer and the different hydrocarbon unitsin the alcohols. For example, the PHA can be poly3-hydroxybutyrate-co-3-hydroxypropionate, the alcohols can be methanoland ethanol, and the esters can be methyl 3-hydroxybutyrate, methyl3-hydroxypropionate, ethyl 3-hydroxybutyrate and ethyl3-hydroxypropionate.

The esters can be used in various applications. For example, an estercan be used as a chiral synthetic building block (e.g., R-methyl3-hydroxy butyrate).

As another example, ethyl 3-hydroxybutyrate can be used as a watermiscible biodegradable cleaning solvent (e.g., in inks and/or fluxes).

In some embodiments, an ester can serve as a solvent, such as acoalescing solvent (e.g., to promote film from latex compositions, suchas paints, which can contain an emulsion or suspension of polymerparticles in an aqueous medium). When present in a liquid mixture (e.g.,latex composition), the ester can form from about 0.05 weight percent toabout 25 weight percent of the mixture. An ester can, for example,reduce a glass transition temperature of composition during the dryingand film forming process. An ester can, for example, reduce the volatileorganic content in aqueous-based polymer compositions. The esters can,for example, reduce the film forming temperature of a composition. Anester can, for example, evaporate over time (e.g., within about fivedays) after film formation, and thereby be removed from the film afterformation. An ester can, for example, act as an adhesion promoter, andpromote the adhesion of solvent based inks (e.g., lithographic inks,gravure inks), solvent based paints or coatings, and/or epoxidebased-paints or coatings.

Amides

Treating a PHA to form an amide generally includes combining the PHAwith an amine (e.g., a primary amine, a secondary amine), and usingelevated temperature and/or pressure.

In general, the amine can be selected as desired. In some embodiments,the amine is an aliphatic primary amine (e.g., an aliphatic primaryamine having up to 20 carbon atoms). In certain embodiments, the amineis an oxygen-containing amine (e.g., mono-ethanolamine,di-ethanolamine). In some embodiments, the amine is a diamine (e.g., anethylene diamine). In certain embodiments, the amine is a cyclic amine.In some embodiments, the amine can be represented by the structureR₈R₉NH, where each of R₈ and R₉ is independently a hydrogen atom or ahydrocarbon radical that contains one or more carbon atoms (e.g., onecarbon atom, two carbon atoms, three carbon atoms, four carbon atoms,five carbon atoms, six carbon atoms, seven carbon atoms, eight carbonatoms, etc.). A hydrocarbon radical can be saturated or unsaturated,substituted or unsubstituted, branched or straight chained, and/orcyclic or acyclic. Examples of substituted hydrocarbon radicals includehalo-substituted hydrocarbon radicals, hydroxy-substituted hydrocarbonradicals, nitrogen-substituted hydrocarbon radicals andoxygen-substituted hydrocarbon radicals. Examples of hydrocarbonradicals include methyl, ethyl, propyl, butyl, 2-ethylhexyl and2-hydroxyethyl.

Examples of amines include ammonia, methyl amine, ethyl amine,pyrrolidone, and 2-hydroxyethyl amine.

In certain embodiments, an amide formed by treating the PHA is analkanoic amide. In some embodiments, an alkanoic amide can berepresented by the structure:

Examples of alkanoic amides include N-methyl 3-hydroxybutyramide,N-ethyl 3-hydroxybutyramide, N-methyl 4-hydroxybutyramide, N-ethyl4-hydroxybutyramide, N-hydroxyethyl 4-hydroxybutyramide,6-hydroxyhexanamide.

In some embodiments, an amide formed by treating a PHA is an alkenoicamide. In certain embodiments, an alkenoic amide can be represented bythe structure.

Without wishing to be bound by theory, it is believed that alkenoicamides can be formed, for example, in an elimination reaction which canoccur prior or subsequent to aminolysis of the PHA or PHA intermediateester bond via reactions that involve dehydration, resulting information of one or more carbon-carbon double bonds. In certainembodiments, alkenoic amides are formed when one or more of R₁, R₂, R₃and R₄ (e.g., one or both of R₃ and R₄) is a hydrogen atom. In someembodiments, alkenoic amides are formed when R₃ and/or R₄ is a hydrogenatom.

Examples of alkenoic amides include acrylamide and methacrylamide.

As noted above, the amide is generally formed by combining the PHA withan amine, and exposing the PHA to elevated temperature and/or elevatedpressure.

In general, the amount of amine used can be selected as desired. Incertain embodiments (e.g., when it is desirable to form an amide forwhich y=0), at least about one mole (e.g., at least about 1.5 moles, atleast about two moles, at least about three moles) of amine is used permole of monomer unit in the PHA and/or at most about 20 moles (e.g., atmost about 10 moles, at most about five moles) of amine are used permole of PHA monomer unit. For example, from about 1.5 moles to about 20moles (e.g., from about 1.5 moles to about five moles) of amine can beused per mole of PHA monomer unit. In some embodiments (e.g., when it isdesirable to form amide for which y>0), less than one mole (e.g., lessthan about 0.9 mole, less than about 0.75 mole, less than about 0.5moles) of amine is used per mole of monomer unit in the PHA.

The temperature can generally be selected as desired. Typically, thetemperature greater than about 25° C. (e.g., at least about 40° C., atleast about 50° C., at least about 60° C.). In some embodiments, thetemperature can be at most about 100° C. (e.g., at most about 90° C., atmost about 80° C.). For example, the temperature can be from about 40°C. to about 90° C. (e.g., from about 50° C. to about 90° C., from about60° C. to about 90° C.

Generally, the pressure can be selected as desired. In some embodiments,the pressure is about 14 psig. In certain embodiment, the pressure isgreater than about 14 psig (e.g., at least about 50 psig, at least about100 psig) and/or at most about 500 psig (e.g., at most about 250 psig).For example, the pressure can be from about 50 psig to about 500 psig.Typically, elevated pressure is achieved using nitrogen, although othergases, such as an inert gases, can be used (e.g., helium, argon,krypton, xenon, etc.).

In certain embodiments, the PHA can be treated while using relativelylittle solvent (e.g., relatively halogenated solvent) other than theamine. For example, the total amount of solvent other than the minepresent during the treatment of the PHA to form the amide can be lessthan one milliliter (e.g., less than about 0.9 milliliter, less thanabout 0.8 milliliter, less than about 0.7 milliliter, less than about0.6 milliliter, less than about 0.5 milliliter, less than about 0.4milliliter, less than about 0.3 milliliter, less than about 0.2milliliter, less than about 0.1 milliliter, less than about 0.05milliliter, about zero milliliter) per gram of PHA.

In certain embodiments, the amount of undesired byproducts is relativelylow. For example, in some embodiments where alkanoic amides are beingprepared, it can be undesirable to form alkenoic byproducts. In someembodiments, the percent yield of undesirable byproducts (e.g., alkenoicbyproducts) from the PHA is less than about 10% (e.g., less than abouteight percent, less than about five percent, less than about threepercent, less than about one percent).

In some embodiments, an amide can be formed from the PHA at a relativelyhigh percent yield. For example, the percent yield of amide from the PHAcan be at least about 50% (e.g., at least about 60%, at least about 70%,at least about 80%, at least about 90%, at least about 95%, at leastabout 98%).

In certain embodiments, an acyclic amide formed via the treatment of aPHA can be further treated to form a cyclic amide (e.g., a lactam). Insome embodiments, the cyclic amide has a ring with at least four carbonatoms (e.g., five carbon atoms, six carbon atoms, seven carbon atoms,eight carbon atoms, nine carbon atoms, ten carbon atoms. In someembodiments, a cyclic amide has the following structure:

As an example, N-methylpyrrolidone can be formed from N-methyl4-hydroxybutyramide (e.g., N-methyl 4-hydroxybutyramide formed bytreating poly 4-hydroxybutyrate and methylamine). As another example,N-ethypyrrolidone can be formed from N-ethyl 4-hydroxybutyramide (e.g.,ethyl 4-hydroxybutyramide formed by treating formed by treating poly4-hydroxybutyrate and ethylamine). As another example,N-hydroxyethylpyrrolidone can be formed from N-ethyl 4-hydroxybutyramide(e.g., N-hydroxyethyl 4-hydroxybutyramide formed by treating poly4-hydroxybutyrate and hydroxyethylamine).

In general, forming a cyclic amide from an acyclic amide includesheating the acyclic amide to a temperature of at least about 100° C.(e.g., at least about 200° C., at least about 250° C., at least about275° C.) at a pressure of at least about 50 psig (at least about 100psig, at least about 250 psig, at least about 500 psig) of nitrogen orone or more other gases (e.g., an inert gas, such as helium, argon,krypton, xenon, etc.).

In some embodiments, the percent yield of cyclic amide from acyclicamide is at least about 50% (e.g., at least about 60%, at least about70%, at least about 80%, at least about 90%, at least about 95%, atleast about 98%). In certain embodiments, the percent yield of cyclicamide from the PHA is at least about 50% (e.g., at least about 60%, atleast about 70%, at least about 80%, at least about 90%, at least about95%, at least about 98%).

In some embodiments in which the PHA is derived from biomass, most ofthe acyclic amide that is formed from the PHA is not removed from thebiomass before being treated to form the cyclic amide. For example, incertain embodiments, less than about 50 weight percent (e.g., less thanabout 40 weight percent, less than about 30 weight percent, less thanabout 20 weight percent, less than about 10 weight percent, less thanabout weight percent five weight percent, less than about three weightpercent, less than about one weight percent, about zero weight percent)of the acyclic amide that is treated to form the cyclic amide is removedfrom the biomass before being treated to form the cyclic amide.

The methods can further include isolating at least a portion of theamide formed by treating the PHA. For example, in embodiments in whichthe PHA is derived from biomass and the PHA is not removed from thebiomass before being treated to form the amide, the methods can includeremoving at least a portion (e.g., at least about 10 weight percent, atleast about 20 weight percent, at least about 30 weight percent, atleast about 40 weight percent, at least about 50 weight percent, atleast about 60 weight percent, at least about 70 weight percent, atleast about 80 weight percent, at least about 90 weight percent, atleast about 95 weight percent, at least about 98 weight percent) of theamide from the biomass.

In embodiments in which the PHA is a PHA copolymer, multiple amides canbe formed, corresponding to the monomer unit in the PHA copolymers andthe amine. For example, the PHA can be poly3-hydroxybutyrate-co-3-hydroxypropionate, the amine can be methylamine,and the amides can be N-methyl 3-hydroxybutyramide and N-methyl3-hydroxypropionamide.

In embodiments in which a PHA homopolymer is combined with differentamines and treated as described above to form amides, multiples amidescan be formed, corresponding to the monomer unit contained in the PHAhomopolymer and the amines. For example, the PHA can be poly3-hydroxybutyrate, the amines can be methylamine and ethylamine, and theamides can be N-methyl 3-hydroxybutyramide and N-ethyl3-hydroxybutyramide.

In embodiments in which the PHA is a PHA copolymer and multiple aminesare used, multiple amides can be formed, corresponding to the differentmonomer units in the copolymer and the different amines. For example,the PHA can be poly 3-hydroxybutyrate-co-3-hydroxypropionate, the aminescan be methylamine and ethylamine, and the amides can be N-methyl3-hydroxybutyramide, N-methyl 3-hydroxypropionamide, N-ethyl3-hydroxybutyramide and N-ethyl 3-hydroxypropionamide.

The amides can be used in a variety of applications. For example,N-hydroxyethyl pyrrolidone can be used to produce N-vinyl pyrrolidone,which, in turn, can be used to produce polyvinylpyrrolidone, which canbe used, for example, in adhesive applications, as a thickener, and/oras a flocculent. As another example, 3-hydroxypropanamide can be used toproduce acrylamide, which, in turn, can be used to producepolyacrylamide, which can be used, for example, in a compositioncontaining moisture absorbing polymers. As a further example, N-methylpyrrolidone can be used as a carrier solvent for paint, ink, adhesiveformulations, as a cleaning/degreasing solvent, and/or as a component inpaint stripper formulations.

Diols

In general, treating a PHA to form a diol includes hydrogenolyzing thePHA. Typically, this includes heating the PHA in the presence of areducing species (e.g., reducing agent). Optionally, this can be done inthe presence of a solvent and/or a catalyst. In some embodiments,elevated pressure is used (e.g., elevated pressure of hydrogen gas).

Typically, the PHA is heated to a temperature of at least about 100° C.(e.g., at least about 150° C., at least about 160° C.). In someembodiments, the temperature is at most about 260° C. (e.g., at mostabout 230° C.). For example, the temperature can be from about 100° C.to about 260° C. (e.g., from about 130° C. to about 230° C., from about160° C. to about 230° C.).

In certain embodiments, a diol formed by treating a PHA has thestructure:

Examples of diols include 1,4-butanediol, 1,3-propanediol,1,3-butanediol, 1,6-hexanediol, 1,3-pentanediol, 1,3-hexanediol,1,3-octanediol, 1,2-propanediol, ethylene glycol and propylene glycol.

In embodiments in which a solvent is used, the solvent can generally beselected as desired. In some embodiments, the solvent is an alcohol.Examples of alcohols include C₁-C₄ alcohols, such as methanol, ethanol,propanol and butanol. In some embodiments, an alcohol solvent can be thesame as the diol being formed by treating the PHA.

In embodiments in which a solvent is used, the concentration of PHA inthe solvent is at least about five weight percent (e.g., at least about10 weight percent). In some embodiments, the concentration of PHA in thesolvent is at most about 90 weight percent (e.g., at most about 50weight percent). For example, the concentration of PHA in the solventcan be from about five weight percent to about 90 weight percent (e.g.,from about five weight percent to about 90 weight percent).

In certain embodiments, the PHA can be treated while using relativelylittle solvent (e.g., relatively little halogenated solvent) other thanthe alcohol. For example, the total amount of solvent other than thealcohol present during the treatment of the PHA to form the ester can beless than one milliliter (e.g., less than about 0.9 milliliter, lessthan about 0.8 milliliter, less than about 0.7 milliliter, less thanabout 0.6 milliliter, less than about 0.5 milliliter, less than about0.4 milliliter, less than about 0.3 milliliter, less than about 0.2milliliter, less than about 0.1 milliliter, less than about 0.05milliliter, about zero milliliter) per gram of PHA.

Generally, in embodiments in which hydrogen is used as the reducingspecies, elevated pressure is used. In some embodiments, the pressure(e.g., hydrogen pressure) used is at least about 200 psig (e.g., atleast about 500 psig, at least about 1000 psig, at least about 2500psig, at least about 3000 psig). In certain embodiments, the pressure(e.g., hydrogen pressure) is at most about 5000 psig (e.g., at mostabout 4000 psig). Other gases (e.g., nitrogen) may be used in additionto hydrogen.

In embodiments in which the PHA treatment to form the diol is performedin the presence of a catalyst, the catalyst is typically a metalcatalyst. Examples of catalysts include copper chromite catalysts,platinum catalysts, (e.g., 2,4-Pentanedionate Platinum (II),Dichloro(norbornadiene)platinum (II)), palladium catalysts (e.g.,Palladium (II) Acetate Trimer, Tris(dibenzylideneacetone)dipalladium(0),trans-Dichlorobis(triphenylphosphine)palladium (II)), nickel complexes,rainey nickel, ruthinium catalysts (e.g., ruthinium dichloridebis-(triphenylphosphine)(1,2-ethanediamine), ruthinium dichloridebis-(tri-p-tolylphosphine)(1,2-ethanediamine)), cobalt, rhodiumcatalysts (e.g., 2,4-Pentanedionate rhodium, Rhodium (III),Chloro(norbornanediene)rhodium (I) Dimer, Rhodium (II) Octanoate Dimer),Iridium catalysts (e.g., 2,4-Pentanedionate Iridium (III) andHydridocarbonyltris(triphenylphosphine)iridium (I)).

Generally, in embodiments in which a catalyst is used, the amount ofcatalyst can be selected as desired. In some embodiments, the catalystcan be at least about 0.1 weight percent (e.g., at least about 0.25weight percent, at least about 0.5 weight percent, at least about oneweight percent) of the total amount of PHA present when the catalyst isadded. In certain embodiments, the catalyst can be at most about 10weight percent (e.g., at most about five weight percent, at most aboutthree weight percent) of the total the total amount of PHA present whenthe catalyst is added. For example, the catalyst can be from about 0.1weight percent to about 10 weight percent (e.g., from about 0.25 weightpercent to about five weight percent of the total the total amount ofPHA present when the catalyst is added.

In embodiments in which the PHA treatment to form the diol is performedin the presence of a reducing agent, the reducing agent can be an activemetal hydride. Examples of reducing agents include lithium aluminumhydride, sodium aluminum hydride, sodium borohydride and Vitride(Zealand Chemicals).

In general, at least about two (e.g., at least about 2.5, at least aboutthree) equivalents of reducing agent are used per mole of PHA monomerunit converted to diol.

In certain embodiments, the amount of undesired byproducts is relativelysmall. For example, alkenoic byproducts can be undesired. In someembodiments, the percent yield of undesirable byproducts (e.g., alkenoicbyproducts) from the PHA is less than about 10% (e.g., less than abouteight percent, less than about five percent, less than about threepercent, less than about one percent).

In some embodiments, the methods result in a relatively high yield ofthe diol. For example, the percent yield of the diol from the PHA can beat least about 30% (e.g., at least about 35%, at least about 40%, atleast about 45%, at least about 50%, at least about 55%, at least about60%, at least about 65%, at least about 70%, at least about 75%, atleast about 80%, at least about 85%, at least about 90%, at least about95%, at least about 98%).

In embodiments in which the PHA is a chiral PHA, the diol can be achiral diol, and the percent chirality yield of chiral diol can berelatively high. For example, the percent chirality yield of a chiraldiol from a chiral PHA can be at least about five percent (e.g., atleast about 10%, at least about 25%, at least about 50%, at least about75%, at least about 85%, at least about 90%, at least about 95%, atleast about 98%).

The diols can be used in a variety of applications. As an example, adiol can be used in aromatic polyester production. As another example,chiral diols (e.g., the D-isomer of 1,3-butanediol from poly3-hydroxybutyrate) can be used in pharmaceutical derivatives and/ornutraceutical derivatives (e.g., via the reaction of chiral1,3-butanediol with chiral D-3-hydroxybutyrate and/or acetoacetate toprovide a chiral ester). As a further example, 1,4-butanediol (e.g.,from poly 4-hydroxybutyrate) can be useful in the production of aromaticpolyesters, tetrahydrofuran, gamma butyrolactone, aliphatic polyesters,urethanes and elastomers. As an additional example, 1,6-hexane diol(e.g., from poly 6-hydroxyhexanoate) is commonly used in polyurethanesand polyester resins. 1,3-butanediol, 1,3-pentanediol and/or1,3-hexanediol can also be combined with diacids (e.g., adipic acid,terephthalic acid, succinic anhydride) to form polyester resins.

Alkenoic Acids

In general, treating a PHA to form an alkenoic acid (e.g., a1,2-unsaturated acid, a 2,3-unsaturated acid) includes heating the PHA.

Typically, the PHA is heated to a temperature of at least about 100° C.(e.g., at least about 150° C., at least about 200° C., at least about250° C.). In certain embodiments, the PHA is heated to a temperature ofat most about 300° C.

Generally, the pressure used when heating the PHA can be selected asdesired. As an example, the PHA can be heated at atmospheric pressure(e.g., while exposed to air or inert gas). As another example, the PHAcan be heated at elevated pressure.

In certain embodiments, an alkenoic acid formed by treating a PHA hasthe structure:

Examples of alkenoic acids include acrylic acid, crotonic acid,pentenoic acid, octenoic acid, ethyl crotonate, methyl crotonate, butylcrotonate, 2-ethylhexyl crotonate, ethyl 2-octenoate, ethyl 2pentenoate, ethyl 2-decanoate and vinyl acetic acid.

In certain embodiments, the PHA can be treated while using relativelylittle or no solvent (e.g., relatively little halogenated solvent). Forexample, the total amount of solvent present during the treatment of thePHA to form the alkenoic acid can be less than one milliliter (e.g.,less than about 0.9 milliliter, less than about 0.8 milliliter, lessthan about 0.7 milliliter, less than about 0.6 milliliter, less thanabout 0.5 milliliter, less than about 0.4 milliliter, less than about0.3 milliliter, less than about 0.2 milliliter, less than about 0.1milliliter, less than about 0.05 milliliter, about zero milliliter) pergram of PHA.

In some embodiments, an alkenoic acid can be formed from the PHA at arelatively high percent yield. For example, the percent yield ofalkenoic acid from the PHA can be at least about 50% (e.g., at leastabout 60%, at least about 70%, at least about 80%, at least about 90%,at least about 95%, at least about 98%). In some embodiments, thesepercent yields of alkenoic acid are achieved using PHA derived frombiomass when less than about 50 weight percent (e.g., less than about 40weight percent, less than about 30 weight percent, less than about 20weight percent, less than about 10 weight percent, less than aboutweight percent five weight percent, less than about three weightpercent, less than about one weight percent, about zero weight percent)of the PHA that is treated to form the alkenoic acid is removed from thebiomass before being treated to form the alkenoic acid.

The methods can further include isolating at least a portion of thealkenoic acid formed by treating the PHA. For example, in embodiments inwhich the PHA is derived from biomass and the PHA is not removed fromthe biomass before being treated to form the amide, the methods caninclude removing at least a portion (e.g., at least about 10 weightpercent, at least about 20 weight percent, at least about 30 weightpercent, at least about 40 weight percent, at least about 50 weightpercent, at least about 60 weight percent, at least about 70 weightpercent, at least about 80 weight percent, at least about 90 weightpercent, at least about 95 weight percent, at least about 98 weightpercent) of the alkenoic acid from the biomass. In some embodiments, thetemperatures used (e.g., at least about 200° C.) volatilize the alkenoicacid.

In embodiments where the PHA is a copolymer, different alkenoic acidscan be formed corresponding to the different monomer units in the PHAcopolymer. As an example, the PHA can be poly3-hydroxybutyrate-co-3-hydroxyvalerate, and the alkenoic acids can becrotonic acid, pentenoic acid, 2-pentenoic acid, 2-butenoic acid and/or2 octenoic acid.

The alkenoic acids can be used in various applications.

In some embodiments, an alkenoic acid can be used in a polymerizationprocess (e.g., a free radical polymerization process) to form a usefulmaterial. As an example, crotonic acid can be used in a free radicalpolymerization process to form a vinyl acetate-crotonate copolymer foruse in hair spray formulations. As another example, acrylic acid can beused within polymerization processes to produce polyacrylate resins foruse in paints, adhesives, coatings, thickeners (e.g., aqueousthickeners), resins (e.g., thermoplastic resins) and modifiers (e.g.,impact modifiers).

The following examples are illustrative and not intended as limiting.

EXAMPLE 1

Ethyl-3-hydroxybutyrate was prepared from a PHA (poly 3-hydroxybutyrate)as follows. A solution of 1.0 g of poly 3-hydroxybutyrate (94% purity)in 4.0 ml of absolute ethanol was prepared in a glass pressure bottle.The PHA was derived from biomass. 10.5 mg of di-butyl tin oxide and 0.5ml of diphenylmethane were added as a catalyst and as an internal gaschromatographic standard, respectively. The mixture was heated to 180°C. with magnetic stirring. After 2.0 hours the percent yield ofethyl-hydroxybutyrate from the PHA was 77.8%, and after 4.0 hours thepercent yield of ethyl-hydroxybutyrate from the PHA was 92%.

EXAMPLE 2

Example 1 was repeated at 200° C., and after two hours of reaction timethe percent yield of ethyl-3-hydroxybutyrate from the PHA was 82.2%.

EXAMPLE 3

Example 2 was repeated except that 10.5 mg of titaniumtetra-isopropoxide was used as the catalyst. After two hours of reactiontime, the percent yield of ethyl-3-hydroxybutyrate from PHA was 82.2%.

EXAMPLE 4

N-methyl 4-hydroxybutyramide was prepared by treating a PHA (poly4-hydroxybutyrate) as follows. A 300 ml 316 stainless steel autoclaveequipped with a stirrer, a gas inlet line, a vent line and a rupturedisc was charged with 13.1 g of poly 4-hydroxybutyrate and 20 g ofmethylamine. The PHA had been isolated from biomass. The autoclave was:flushed with nitrogen; put under 100 psig of nitrogen; heated withstirring to 80° C.; and held at this temperature for 5.0 hours. Theautoclave was then cooled to room temperature, vented and opened. ThePHA was completely consumed. The excess methylamine was removed under anitrogen stream, and the remaining dark brown liquid analyzed via gaschromatography (GC). The GC trace on a boiling point column showed onlyone component, and that point corresponded to N-methyl4-hydroxybutyramide.

EXAMPLE 5

N-Methylpyrrolidone was prepared as follows. The liquid from Example 4was heated under nitrogen with stirring in the same autoclave to 280° C.and held at that temperature for two hours. The pressure was 600 psig.After cooling, the clave was opened and the liquid contents dischargedand analyzed via GC. The majority of the liquid was methylpyrrolidone,and the remainder of the liquid was unreacted amide having the sameretention time as the starting amide. At 100% polymer conversion, thepercent yield of methylpyrrolidone from PHA was in excess of 90%.

EXAMPLE 6

1,4-Butanediol was prepared from a PHA (poly 4-hydroxybutyrate) asfollows. A one liter autoclave was charged with 40 g of poly4-hydroxybutyrate, 400 g of methanol and 5.0 g of powdered bariumpromoted copper chromite obtained from Engelhard. The PHA had beenisolated from biomass. The clave was pressured with hydrogen to 200 psigand the pressure was released. This was done four times and the clavethen pressured to 2000 psig with hydrogen. The clave was then heatedwith stirring to 160° C. and the final pressure adjusted to 3500 psigwith hydrogen. The clave was kept at 160° C. for 2.0 hours, and thetemperature then raised to 180° C. for an additional 2.0 hours. Thepressure was adjusted to 3500 psig. Finally, the temperature was raisedto 200° C. for an additional 2.0 hours, again at 3500 psig hydrogen. Theclave was then cooled to room temperature and vented. Any remaininghydrogen was purged with nitrogen and the contents discharged. There wasno solid PHA left, and the solution was water white. Analysis of thesolution by GC after filtering off the catalyst showed that the majorproduct was 1,4-butanediol.

EXAMPLE 7

Crotonic acid was prepared from a PHA (poly 3-hydroxybutyrate) asfollows. Seven grams of biomass (with most water removed, butnon-lyophilized) from the fermentation process of poly 3-hydroxybutyrate(comprising 4.3 g poly 3-hydroxybutyrate having a molecularweight>700,000, 2.1 g of cell components and 0.6 g of inorganic saltsremaining from the fermentation media) was heated at 245° C. in an airatmosphere. After 30 minutes, no further volatile components wereobserved. The volatile component was analyzed by GC. The yield ofalkenoic acid component was 98.0% based on the poly 3-hydroxybutyratecomponent of the biomass. The composition of the alkenoic acid fractionwas 96% crotonic acid, and no unsaturated dimer or trimer was detected.

EXAMPLE 8

Crotonic acid was prepared from a PHA (poly 3-hydroxybutyrate) asfollows. Eight grams of biomass (with most water removed, butnon-lyophilized) from the fermentation process of poly 3-hydroxybutyratewashed free of soluble inorganic salts (comprising 5.7 g poly3-hydroxybutyrate having a molecular weight>700,000, 2.3 g of cellcomponents) was heated at 245° C. in an air atmosphere. After 30 minutesno further volatile components were observed. The volatile component wasanalyzed by GC. The yield of the alkenoic acid component was 96.8.0%based on the poly 3-hydroxybutyrate component of the biomass. Thecomposition of alkenoic acid fraction: 95.5% crotonic acid, and nounsaturated dimer or trimer was detected.

EXAMPLE 9

2-ethylhexyl R-3-hydroxybutyrate was prepared from a PHA (ethylR-3-hydroxybutyrate) as follows. 132 g of ethyl R-3-hydroxybutyrate werecombined with 130 g of 2-ethylhexanol and 0.5 g of sulfuric acidcatalyst. The mixture was heated to a temperature of 140° C. for 2hours, and the ethanol removed by fractional distillation. Gaschromatography (GC) identified the resultant product as being 98% pure2-ethylhexyl R-3-hydroxybutyrate with the following pr 495-502° F.;flash point (closed cup): 260° F.; kinematic viscosity: 11.06 cSt; andrelative evaporation rate: <0.01 (butyl acetate=1).

EXAMPLE 10

Cyclohexyl R-3-hydroxybutyrate was prepared from a PHA(poly-R-3-hydroxybutyrate) as follows. 900 mL of cyclohexanol, 200 gramsof poly-R-3-hydroxybutyrate and 5.26 grams of dibutyl-tin oxide werereacted at 142-147° C. for 8 hours. The crude brown product was filteredand short-path distilled. The first distillate was 560 mL of purecyclohexanol. The second distillate was clear cyclohexyl ester withpurity by GC of 97.6% and had the following physical properties: boilingpoint at atmospheric pressure: 485-502° F.; flash point (closed cup):255° F.; kinematic viscosity: 28.87 cSt; relative evaporation rate:<0.01 (butyl acetate=1).

EXAMPLE 11

4-methylcyclohexyl R-3-hydroxybutyrate was prepared frompoly-R-3-hydroxybutyrate as follows. 900 mL of methylcyclohexanol, 200grams of poly-R-3-hydroxybutyrate and 5.26 grams of dibutyl-tin oxidewere reacted at 142-147° C. for 8 hours. The crude brown product wasfiltered and short-path distilled. The first distillate was 560 mL ofpure methylcyclohexanol. The second distillate was clearmethylcyclohexyl ester with purity by GC of 97.6% and had the followingphysical properties: boiling point at atmospheric pressure: 459-485° F.;flash point (closed cup): 262° F.; kinematic viscosity: 30.49 cSt; andrelative evaporation rate: <0.01 (butyl acetate=1).

EVALUATION OF EXAMPLES 9 THROUGH 11 IN COATING SYSTEMS

The following evaluation was performed independently for each of thesolvents prepared in Examples 9-11. The solvent was slowly added to 50 gof emulsion under continuous stirring for at least 10 minutes. Thestability of the system was determined by allowing the emulsion to standfor 24 hours and the consistency visually determined to see if any phaseseparation or gel formation had developed.

The glass transition temperature (Tg) for the polymer, and the blendswas determined by placing a small sample of the emulsion onto a glassplate and allowing the water to evaporate. The dried material was thentransferred to a Perkin Elmer DSC and heated from −50° C. to +100° C. at10° C./minute. The mid point glass transition temperature was determinedfrom the inflection in the heat capacity versus temperature curve.

Film forming properties were determined by storing the emulsion in arefrigerator at 5° C. overnight with a number of clean glass plates. Awet polymer film approximately 100-200 microns in thickness was appliedto the glass plates which were then stored again in the refrigerator forseveral days. After this time period, the films were examined forintegrity and strength.

phr on dry Film forming Polymer grade solvent polymer stability Tg (C)properties 5C Airflex 30 None None stable +32 No film, Polyvinyl powderyacetate Ex. 9 3.2 stable −5.2 Tough clear film Ex. 9 6.8 stable −11.1Tough clear film Ex. 10 3.2 stable −4.6 Tough clear film Ex. 11 3.5stable −4.9 Tough clear film Airflex 4514 None None stable 69.4 No film,Polyvinyl powdery chloride Ex. 9 3.2 stable 10.2 No film, powdery Ex. 97.2 stable −7.2 Tough clear film Ex. 9 14.8  stable −15.2 Tough clearfilm Nacrylic 2500 None None stable 24 No film, Acrylic powderycopolymer Ex. 9 7.2 stable −5.2 Tough clear film Ex. 9 14.4  stable−24.4 Tough clear film Nacrylic 6408 None None stable 52 No film,Acrylic powdery copolymer Ex. 9 8.6 stable 2.3 Tough slightly opaquefilm Ex. 9 14.4  stable −24.3 Tough clear film

Other embodiments are in the claims.

1. A method of making a diol from a PHA, comprising: hydrogenolyzing aPHA to form a diol, wherein the PHA contains at least about 500 monomerunits, and the monomer units are selected from the group consisting of3-hydroxypropionate, 4-hydroxybutyrate, 4-hydroxypentanoate,5-hydroxypentanoate, and combinations thereof.
 2. The method of claim 1,wherein the PHA is hydrogenolyzed at a temperature of at least about100° C.
 3. The method of claim 1, wherein the percent yield of diol fromthe PHA is at least about five percent.
 4. The method of claim 1,wherein the PHA is a chiral PHA, and a percent chirality yield of chiraldiol is at least about five percent.
 5. The method of claim 1, whereinhydrogenolysis occurs in the presence of a hydrogen-containing gas. 6.The method of claim 5, wherein the hydrogen-containing gas compriseshydrogen gas.
 7. The method of claim 1, wherein the PHA is derived froma biomass.
 8. The method of claim 7, wherein the biomass is selectedfrom the group consisting of plant biomass and microbial biomass.
 9. Themethod of claim 7, wherein the biomass is non-lyophilized.
 10. Themethod of claim 7, wherein less than about 50 weight percent of the PHAthat is treated to form the diol is removed from the biomass beforebeing treated to form the diol.
 11. The method of claim 1, furthercomprising contacting the PHA with a reducing agent duringhydrogenolysis.
 12. The method of claim 1, further comprising contactingthe PHA with a catalyst during hydrogenolysis.
 13. The method of claim1, further comprising combining the PHA with a solvent.
 14. The methodof claim 1, wherein the diol has the structure:

and wherein n is selected from the group consisting of zero and aninteger greater than zero, and each of R₁, R₂, R₃, R₄, R₅ and R₆ isindependently selected from the group consisting of a hydrogen atom, ahalogen atom and a hydrocarbon radical.
 15. The method of claim 14,wherein n is zero, one or two.
 16. The method of claim 15, wherein R₂,R₃ and R₄ are each hydrogen atoms.
 17. The method of claim 16, whereinR₁ is selected from the group consisting of a hydrogen atom, a methylradical, an ethyl radical, a propyl radical, a butyl radical and apentyl radical.
 18. The method of claim 1, wherein the PHA is selectedfrom the group consisting of poly 3-hydroxypropionate, poly4-hydroxybutyrate, poly 4-hydroxypentanoate, and poly5-hydroxypentanoate.
 19. The method of claim 1, wherein the diol isselected from the group consisting of 1,4-butanediol, 1,3-propanediol,1,4-pentanediol, 1,5-pentanediol, 3-butanediol, 1,3-pentanediol,1,3-hexanediol, 1,3-octanediol and 1,2-propanediol.
 20. The method ofclaim 1, wherein the PHA is contacted with the transition metal catalystin the substantial absence of a halogenated solvent.
 21. The method ofclaim 1, wherein the diol is formed without first forming a hydroxyacid.
 22. The method of claim 1, wherein the diol contains only onemonomer unit from the PHA.
 23. The method of claim 13, wherein thesolvent comprises an alcohol.
 24. The method of claim 23, wherein thealcohol comprises a diol.
 25. The method of claim 24, wherein the diolcomprises the same diol as formed by treating the PHA.
 26. The method ofclaim 24, further comprising reacting the diol to form a cyclic ether.27. The method of claim 26, wherein the cyclic ether comprises polyetherpolyol.